Ok, ladies and gentlemen I'm here with your independent review... I own no stock in any company and could care less how well or not well this case sells. With that:
I am a sucker for clear iPhone cases. I love the look of the iPhone and wish it wasn't all glass so a case wouldn't be totally necessary. I have tried several and where I liked many including the Powersupport Air Jacket and the clear Incase Snap, the biggest beef I have with them is they all scratch badly within minutes.
Recently I have begun using the Incipio NGP smoke colored as it's the closest thing in TPU they offer that you can still see the Apple logo and backing. I like this case but don't love it. Kinda bulky but whatever. It's passable.
When reading this thread the other day I drank the Kool Aid and ordered knowing the Zum was on sale at Amazon for $12.99. I 'm already a Prime member so 2 day shipping was free. I figured it was worth a shot for the price. I received today and here are some initial impressions:
The case is definitely worth $12.99. Both the sleep and volume buttons work perfect. I believe someone used the word natural for the button response in an earlier post. That would be a perfect description. No problem with the buttons. The case is slim especially compared to the Incipio NGP. If I had a beef with it I would say the TPU isn't the best quality but again it's not bad. Just not great. The bottom front lip seems quite flimsy and could be a problem down the line, but now. I would say the backing isn't as crystal clear as hard plastic, maybe a slight frosting but for a TPU material, I like it since it's been a few hours and not one scratch. Hurray! I'm not a fan of the charge port flap and probably will cut it off but both the charge port flap and phone jack flap are secure when in.
Overall, again for $12.99, I'm not complaining. The case does look and feel good on my 4s. Hopefully this unbiased, independent review has helped.